If it is web application
as ur textboxes are on differnt page , u can store both values in session and can compare like.
session["Total"]=txtTotal.text;
session["sales"]=txtsalesorder.text;
on the page u want to compare u can do like
if(session["Total"].tostring()==session["sales"].tostring())
txtorderstatus.text=paid;
If it is windows
ucan store textboxvalue in string like
string Total=txtTotal.text;
on other page u can retreive like
Form1.Total